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Патент USA US2404944

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July 30, 1946.
Filed April 29,‘ 1943
4 Sheéts-Shee’c l
July 30, 1946.
Filed April 29, 1943
4 Sheets-Sheet 2
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July 30, 1946.
Filed April 29, 1943‘
4 Sheets-Sheet 3
?éWMAA/A 59435397
July 30, 1946“
Filed April 29, 1943
4 Sheets-Sheet 4
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Patented‘July 30, 1946
2,404,944 ‘
arraaa'rus roa aanoc'rron or oxmas
Herman A. Brassert, Washington, Conn., assignor
to H. A. Brassert & Company, New York, N. Y.,
a corporation of Illinois
Application April 29, 1943, Serial No. 484,960
6 Claims.
(or. ace-21)
This invention relates to apparatus for fa
cilitating and controlling chemical reactions be
tween ?nely-divided solids and ?uids, and has
particular reference to apparatus for the reduc
in a cumulative effect, which makes uniform dis
tribution of gas in the ore bed impossible.
It has been found that these di?iculties may
be avoided by maintaining a de?nite relation be
tion of ?nely-divided metallic ores or other oxides
tween the volume of the gas that is necessary to
by reducing gases, or to the desulphurization'or
reduce the ore, the nozzle velocity at which the
bene?ciation of such ores or oxides by gases,
gas enters the ore bed, and the velocity at which
although the invention is not ‘limited to such uses.
it traverses the ore bed, and the present invention
One apparatus of effecting such reactions is
is primarily directed to the provision of such
disclosed in application Serial No. 338,560, ?led 10 de?nite relation for the various conditions that
June 3, 1940, by J. C. Hartley, in which preheated
are encountered in the operation of reduction ap
reducing gases are caused to flow through a bed
paratus of the general type described.
of ?nely-divided ore under such conditions that
In accordance with the invention, the hearth
is constructed so that the area of the total gas
the bed assumes a state equivalent to ?uidity, and
hence flows along the hearth from the charging 15 opening in the hearth is increased in such pro
to the discharging point while the ore is reduced.
The preheated reducing gases pass into the ore
bed through a perforate hearth, the particular
form of hearth‘shown in said application being
portion to the hearth area by providing multiple
channels each independently supplied With gas,
that not only is the proper volume of gas sup
plied but a given velocity of gas bears a favorable
provided with directional slots, although other 20 relation to the physical character of the ore bed,
operative forms of perforate hearth give the same
effects, as for example that disclosed in applica
tion Serial No. 422,930, ?led December 15, 1941,
by C. J. Westling. That application discloses a
its depth, and the speci?c gravity of the ore ?nes.
By way of illustration, but not limitation, the in
vention may be a V-shaped hearth type of reduc
tion apparatus in which the number of V-shaped
V-shaped trough hearth, into the bottom of which 25 troughs and the area of the gas openings thereof
may be varied to give the desired area relation
the preheated reducing gases are non-direction
ship necessary for the realization of the advan
ally introduced for. percolation through the ore
of the invention, typical embodiments of
bed to reduce the ore and to impart the fluid-like
which are illustrated in the accompanying draw
condition thereto, so that the bed ?ows along the 30 ings, in which:
Figure 1 is a vertical cross-section through the
The described forms of hearth are efficiently
reduction apparatus, as seen along the line l--i
effective under certain conditions but are not as
of Fig. 3, embodying the invention;
effective when the conditions change. After in
Fig. 2 is a horizontal section through the
vestigation to ascertain the reasons for such lack
hearth-supporting spacers as seen along the line
of ?exibility, it has been found to be generally
2—2 of Fig. 1 and shows their inclination Where
due to'the velocity and volume of the gas, which
by variation in the gas volume may be effected;
is required to perform both functions of ade
Fig. 3 is a longitudinal section through the ap~
quately reducing the ore and maintaining the de
paratus as seen along the line 3-3 of Fig, 1;
hearth while the ore is reduced.
sirable ?uid-like state of the ore bed. For ex 40 Fig. 4 is an enlarged cross-section through a
ample, if'the gas velocity across the ore bed is
modi?ed form of hearth bar, embodying the ad
too great, as when the ore bed lies in one or two
vantages of the venturi effect.
V-channels but into which all the gas is intro
Fig. 5 is a vertical section through a circular
duced at the bottom, the gas may pass through
type of multiple furnace as seen along the line
the ore too rapidly, and cause the very ?ne par 45 5—5 of Fig. 6, and embodying the features of the
ticles of the ore to be projected high above the
furnace of Figs. .1 and 2 and the principles of
bed and be entrained with the out-?owing spent
gases, causing undesirable dust losses. Although
this invention;
Fig, -6 is a transverse section therethrough as
such ?nes can be recovered from the exit gases
seen along the line 6-6 of Fig. 5; and,
after they leave the reducing unit, such recovery 50 Fig. 7 is a fragmentary section through three
is expensive. Furthermore, high gas velocities
of the material transferring pressure locks be
augment, the channeling tendency of the gases
tween the stagesof the furnace, as seen along the
- which, by reason of their high kinetic energy,
open up passages through the ore and continually
line '|—‘| of Fig, 6.
Referring to Figs. 1 and 3 of the drawings,
enlarge them while carrying ore ?nes with them, 55 numeral l0 designates the elongated casing for an
iron ore or other oxide reduction apparatus,
it causes the entire bed to assume a ?uid-like
which is preferably constructed of metal, al
state, as described in said copending applications,
though it may be wholly or partly constructed of
ceramic material, such as ?re brick. At the bot
so that the ore flows from the inlet to the outlet.
The gas is preheated by means not shown, so that
tom of the casing I0 is the reducing gas supply
box ii, into which the gas is brought through
the ore is reduced by the gas at temperatures on
the order of 1100 to 15000 F., below those at which
the particles agglomerate or frit together. Ac
cordingly, the material remains in a finely divided
state throughout the operation, and may be dis
charged over dam 2| to briquetting rolls, while
still hot and in as reducing atmosphere. The re
duced material is accordingly briquetted into self
sustaining units which are uncontaminated by
reoxidation, since the reduced particles do not
one or more pipes l2, from a suitable manifold
or other supply system. Additional gas volume
is supplied at low pressure by pipe i2’ without
materially increasing the pressure in ii.
The gas is preferably preheated hydrogen or
high-hydrogen containing gas, such as coke-oven
gas, and is preferably supplied directly from the
coke-ovens. Other suitable reducing gases may
be employed, such as reformed illuminating or oil
gas, reformed natural gas, reformed blast fur
nace gas, and the like, containing hydrogen
and/or carbon monoxide.
. r
come in contact with air or other oxidation at
mosphere, as described in Patent No. 2,287,663,
issued June 23, 1942, to applicant, to which refer
ence may be had for further details of the method
of handling the material after reduction.
The furnace may be maintained under super
in may be v-shaped in section, as shown, and 20
atmospheric pressure, if desired, by sealing the
suspended across it above the gas box II is the
ore inlet either by supplying the ore through a
hearth l3, preferably made up of an assembly of
self-sealing valve of the star wheel type 22, op
parts of high temperature resisting steel or cast
erated by gravity or power-driven, or by using
iron, ceramic, or other refractory material. The
hearth 03 comprises a series of adjacent bars M 25 a conventional double bell pressure-lock. The
_ spent reducing gas is collected in the hood 23 and
which are generally diamond-shaped in cross
is released at the predetermined pressure through
section with sides sloping about 30° to the vertical,
a gas pressure-operated valve 24 in the gas out
so as to form the V-shaped channels I4’ in and
let 25, the valve being set at the internal gas
above which the ore bed 0 lies to a depth of 41/2 to
30 pressure desired.
12 inches.
Although the fluid-like condition which is im
The bars 14 are preferably supported - and
parted to the ore bed, and which causes it to flow
spaced apart the required distance by spacers I6,
in the manner described in said copending appli
so as to provide slots i5 on the order of 116 inch
cations, requires no additional propulsion, it may
wide between adjacent bars through which the
gas enters from the gas box ll. Spacers l6 are 35 be desirable to control and retard the flow and
break up any gas bubbles by means of stationary
parallel ?at plates arranged in their lowest posi
?ngers 25, mounted on a suitable frame 21, sus
tion at an angle of about 45° and hinged at an
pended from the hood of the apparatus. The
angle on a suitable truss H, as shown in Figs. 2
fingers 26 project downwardly into the ore bed 0,
and 8.
A draw-bar i8 connects spacers l6 and has a 40 and may extend partly into the V-shaped troughs
l4’ thereof. The degree of ?ow control is deter
threaded outer end projecting through the end
mined both by the size of the ?ngers 26 and their
wall of the furnace ?tted with a nut and crank
depth of immersion in the ore bed, and accord
combination i8’, whereby the spacers i6 may be
ingly the ?ngers 26 may be raised or lowered to
raised and lowered to raise and lower the grate
bars Ml. Owing to the increasing angular dis 45 adjust the rate of flow. It may be desirable to
move these ?ngers, for instance at a slower rate
position of spacers I6 to a vertical plane to either
than the flow of the ore bed, in order to increase
side of the center, as shown in Fig. 2, they spread
the time of reduction. The ?ngers may be moved
the bars ill apart as they are raised from the
by any ‘suitable mechanism (not shown).
position shown in Fig. 3, so as to increase the
In order to preclude channeling and dusting,
width of the gas slots [5 between the bars l4, and 50
owing to uneven and improper percolation of the
vice versa, as they are lowered.
reducing gas through the ore bed, while'obtaining
The width of the slots l5 depends upon the
The general shape of the reduction apparatus
and maintaining the ?uid-like condition of the
depth of the bed 0, the physical nature ofpthe
bed, and effective reduction, it has ‘been ascer
ore, the pressure and velocity of the gas issuing
from slots i 5, and the area of the hearth, as well 55 tained that in a reduction apparatus of the type
described, a de?nite relationship must exist be
as the throughput desired for the apparatus,
tween the volume and velocity of the gas for
these factors being variable in accordance with
iron ores or other oxides for any sizes passing a
certain principles of the invention to be de
28 mesh screen, which comprises the range of
scribed. The adjustment in the depth of the bed
may be obtained by raising or lowering the dis 60 ?neness which can be effectively handled. There
is always a certain optimum gas volume-velocity
charge dam 2! by means of a crank and pinion
condition below which the bed progress is too
combination 2 I '.
slow and short-circuiting oi' the gas current oc
In some instances, it may be preferred that
curs, whereas above this condition the gas is likely
the adjacent hearth bars I4 constituting the
hearth l3 be so shaped that the gas passages 65 to form large bubbles and burst through the bed
with consequent channeling and dusting. The
have a Venturi contour, as shown in Fig. 4, where
shallower the ore bed with a given gas volume,
the side walls of the trough l4’ slope at an angle
the greater the danger of channeling and the
of about 30° to the vertical, and the bottom faces
chance of gas bubble formation which actually
I 5 slope at about 45°, the slot [5 thus constituting
the throat of the venturi. This nozzle velocity 70 results in decrease of pressure. In general, for
a given ?neness and quality of oxide and depth
can be regulated by changing the width of the
of bed, the gas volume can be increased and the
slots-I5 as described.
velocity decreased by increasing the width of slots
The ?nely-divided ore is supplied to the hearth
IS in the manner described, and vice versa, or by
[3 at the inlet 20, after being concentrated, and
as the pressure gas percolates through the ore 75 increasing the number of slots l5 and vice versa.
Depending on the nature of the ores and the like,
the gas volume and pressure is regulated to obtain
most efficient reduction. Gas volume and pres
in Fig. 6, the ?ngers 33 tend to sweep the ore
on the corresponding hearth toward the periph
ery and equalize the ?ow rate across the hearth.
sure in gas box ll may be adjusted by valves or
The raw iron ore or other oxide in ?nely
supply pipes I2 and I2’. By increasing the depth
divided state, is supplied to the furnace through
a hopper 35 at the top from which it is fed at a
of the ore bed, the capacity of a given reducing
unit may now be increased to any desirable ex
tent because the ?ow of the gases may be so
constant rate through the gas and pressure-lock
star wheel valve 36, which is driven by a gear
31 fixed to the rotary shaft 3|. A chute 35' dis
charges the material on to upper hearth 29,
regulated as to give substantially perfect perco
lation of the gas through the heavier ore bed
without channeling.
where it is at least partially reduced by reducing
The foregoing conclusions are based upon sub
gas percolating upwardly therethrough from the
stantial experimentation and tests made with
gas space 38 above the second hearth 28. If
different ores, which demonstrated the described
desired air or other oxidizing gas may be ad
gas pressure-volume relationship. These demon 15 mitted through pipe 39 into gas space 38 if it
strations showed that for proper gas volumes and
is desired to roast or desulphurize the ore on
pressures, obtained as described, the ore moved I upper hearth 29. Air may be also supplied for
progressively along the hearth at a uniform rate
supporting combustion of some of the reducing
of speed without dusting and without channeling,
gas and products of reduction, should additional
or the continuous formation of large gas bubbles,
heat be required for roasting or otherwise at the
and with an optimum condition of reduction.
top of the shaft 30. Also, additional hot re
Inasmuch as the ore was of a ?neness of less
ducing gas may be supplied to gas space 38 from
than 28 mesh, the demonstrations included the
manifold 40 for augmenting the reduction of the
range of ?neness effectively handled by appara
ore on upper hearth 29, and increasing the pres
tus embodying the method described, and ac 25 sure and volume of the gas, as well as its tem
cordingly the gas pressures and volumes used for
different depths of ore bed are also usable for
As the ore travels along the slotted multiple V
ores within that ?neness range, it being only
upper hearth 29, aided by the sweeping action
necessary to adjust the gas volume and pressures
of the rotating ?ngers 33, it reaches the radial
for different depths of ore beds as indicated. 30 slot 4| and is discharged over dam 4|’, falling
It will be understood the most advantageous re
to the second hearth 28,,through the gas seal
lation of depth of bed to velocity and pressure
star valve 42, which is driven by gear 43 on
of the gas, must be worked out in actual opera
rotary shaft 3|. The partially reduced material
tion for each type and size of ore unit.
is further reduced on hearth 28 as the gas perco
' These principles and speci?cations are appli 3. lates therethrough from gas space 44 above lower
cable not only to elongated hearths of the gen
hearth 2?. Additional hot reducing gas may be
eral type illustrated in Figs. 1 and 3, but also
supplied to gas space 44 from manifold 40 if
apply to circular reducing apparatus, as for exam
desired, to enrich the partially spent gas from
ple the type generally classi?ed as the Herreshoff
the lower hearth 27 or to increase its pressure,
type, in vwhich the several hearths are arranged v or both, and temperature.
one above the other to conserve space and heat.
As it progresses along the hearth, aided by the
When the hearths are so arranged, the ore
sweeping action of ?ngers 33, the further reduced
charged on the uppermost level is partially re
material discharges through radial slot 45 and
duced and is then discharged to the next level
gas seal star valve 46, driven by gear 41, upon
where it is further reduced, and ?nally it is dis 45 the lower hearth 21 for ?nal reduction. The
charged to the lower level where it is substan
hot gas for reduction is supplied from main 48
and is preheated to the proper temperature to
eifect reduction on the lower hearth 21 at be
tween 1100 and 1500° F., and at the proper
drawings, wherein three circular hearths, each 50 volume and pressure, according to the speci?ca
embodying the characteristics of the hearth of
tions heretofore given for the hearth and depth
Fig. 1, are supplied with reducing gas in succes
of ore bed. The gas is delivered to the gas ring
sion. The fresh reducing gas is supplied from
or box 49.
supply box 49 to the lowermost hearth 21 where
As the material on hearth 21 is ?nally re
it is partially spent, but since it is supplied in 55
duced to metallic iron without fusion or sinter
volume in excess of that required for complete
ing, it reaches slot 50, and discharges directly
reduction of the material on the lower hearth 27,
to the briquetting rolls,» not shown, where it is
it is supplied directly to the second hearth 28
compacted into briquettes while still in a re—'
through which it percolates infthe manner de
ducing atmosphere and still hot, according to
scribed to continue its reducing function, and 60 aforesaid Patent No. 2,287,663.
from there it passes upwardly through the upper
It will be observed that the gas progresses up
hearth 29 where the initial reduction is effected.
wardly through the successive hearths, any de
These three circular hearths 21, 28 and 29, each
sired number of which may be employed. The
constructed like that shown in Fig. 1, are mount
gas collected from the gas space 5| above the
ed above each other within the shaft 30, which 65 upper hearth passes out through ring 52 through
has journalled at its vertical axis a rotary shaft
an automatic pressure responsive valve 53, which
' 3|, driven slowly from a suitable source of power,
is set at the required internal furnace pressure.
not shown, and carrying horizontal arms 32, one
The spent gas may be reformed and returned,
for each hearth. Each arm 32 carries two or
or used for combustion. The purpose of the gas
more sets of ?ngers 33 of thin ?exible material 70 seals 36, 42 and 46 is to prevent the gas from
such as spring steel from 1/4; to 1/2 inch wide.
going up through the ore chutes, and hence
These ?ngers 33 are mounted on a bar 34 ad
it is forced to flow up through the openings at
justable angularly on arm 32, so that the degree
the bottom of the V troughs or corrugations
of sweeping action of the ?ngers 33 may be ad
forming the base of the hearths. The gas pres
justed. Thus, when arranged at the angle shown 75 sure in the furnace is preferably on the order
tially completely reduced before being supplied
to the briquetting apparatus. A reducing appa
ratus of this type is illustrated in Fig. 5 of the
of ten pounds, which is the usual pressure at
which coke oven gas is distributed through steel
works, but it may be lower or higher, but always
su?lciently high to be of substantial moment
in increasing the reducing capacity of the unit.
It is evident that if the pressure is one atmos
phere, or ?fteen pounds, above the barometric,
then twice as much gas being contained in the
unit, the rate of reduction may be nearly
adjusting their dams accordingly, rising gas of_
progressively decreasing reducing power is uti
lized to treat progressively decreasing volumes
of material, as well as more easily reduced ma
terial. In this way the full reducing power
of thegas may be utilized economically, and
without liability of reoxidation of the material.
In both illustrated forms of furnace, the vol
ume of gas may be increased to accommodate
When natural gas is used, which may 10 increased volume of oxide to be reduced, with a
be available at much higher pressure, these
corresponding decrease in the velocity of the gas
pressures may be pro?tably applied to accelerate
percolating through the material. In the fur
nace of Fig. 5, the decrease in velocity of the
gas through the successive beds is effected sub
stantially automatically, as the depth of the
' ores dropping through the openings in the V
beds increase when dams 4!’ are raised, since
hearths, because only the finest will drop through
the gas percolates at a slower rate through the
the narrow slots, and these require the shortest
bottom bed owing to its greater depth, and hence
time for reduction. They will fall on the hearth.
the velocity or the rising gas through the upper
below, and the only effect would be to reduce
their time in the reducing furnace. In the low 20 beds is decreased, the additional gas volume
necessarily being supplied separately to each bed
est hearth on the other hand, the falling through
from manifold 40, controlled by the several cor
of ore ?nes into the gas ducts might be objec
responding valves, or by means of a separate gas
tionable. This can be avoided by using in the
supply, not shown, but similar to H’ in Fig. 1.
bottom section a slotted hearth so designed that
Although the method of this invention has
no ore can fall through, the gas in this case
been described in. connection with several phys
entering through substantially horizontal or
ical embodiments of furnace, it is susceptible or
curved slots so designed as to prevent the fall
use in other types of furnace, and the latter
ing through of ore. A type of such design is
may also be altered within the scope or the ap
shown in said Westling application. ‘
All of the gas may be applied at the bottom 30 pended claims.
I claim:
of the unit to the lowest hearth. The spent
1. In apparatus for reducing ?nely-divided me
gases, after bubbling through the ?rst hearth,
tallic oxide material, the combination of a multi
penetrate into the second, and from the second
ple channel hearth having gas apertures therein,
into the third and so on to the top, where the
means for supplying reducing gas from beneath
final spent gases are taken from the unit. Each
the hearth for ?ow through the apertures thereof
successive hearth would then have a weaker re
to reduce the same and simultaneously maintain
ducing gas, but the reducing strength of the
the material in a state of suspension so that it
original gas, the volume and temperature of the
?ows along the hearth, an adjustable dam at the
gas and the amount of ore coming through the
unit against the flow of the gas would have 40 discharge end of the hearth for adjusting the
depth of the bed, and means for adjusting the
to be proportioned so that the equilibrium of
volume and velocity of the gas supplied to the
reduction will be reached in the top hearth at
hearth in accordance with increase or decrease of
its temperature. In order to make the unit more
bed depth resulting from raising or lowering said’
?exible in this respect, and also in order to re
duce the velocity of the gas going through the
2. In apparatus for reducing ?nely-divided ox
ore bed on each hearth, its velocity is kept down
ide material, the combination of a plurality of
to the desirable point, that is, low enough so
closely-spaced parallel bars of substantially tri
that the gases will not pick up the ?nes from
angular cross-section forming a hearth having a
the bed and whirl them up into the slots of the
plurality of substantially V-shaped grooves hav
hearth next above. Not all of the gas need be
ing bottom slots, a gas chamber beneath said
admitted at the bottom, but some fresh gas may
hearth, means for supplying reducing gas to said
be admitted to one or more hearths above, as
chamber for ?ow through said hearth slots, and
described. By regulating the amounts of the
means for feeding a bed of the ?nely-divided ma
additional gas inflow to the upper hearths, the
process can be so regulated that the equilibrium .7 terial to one end of said hearth for reduction by
said gas.
is nearly reached, and the values of the reducing
3. In apparatus for reducing ?nely-divided ox
, power of the hydrogen and CO in the gas are
material, the combination of a plurality of
utilized to the limit.
closely-spaced parallel bars of substantially tri
With this multiple hearth arrangement the
reduction is progressive from top to bottom and 60 angular cross-section forming a hearth having
a plurality of substantially V-shaped grooves hav
as the oxygen in the fresh oxide on the top
ing bottom slots, a gas chamber beneath said
hearth is more available than that in the largely
hearth, means for supplying reducing gas to said
reduced material on the bottom hearth, the par
chamber for flow through said hearth slots,
tially spent gas percolating through the oxide
the rate of reduction.
No precautions need to be taken against ?ne
on the top hearth is still capable of reducing- '
some of this fresh oxide, even when no fresh
gas is mixed therewith. This same condition
takes place on the intermediate hearths, i. e., a .
means for feeding a bed of the ?nely-divided ma
terial to one end of said hearth for reduction by'
said gas, and an adjustable dam at the discharge
end of said hearth for regulating the depth of the
bed on the hearth.
smaller proportion of unoxidized gas is available,
4. In apparatus for reducing finely-divided ox
as it rises through the furnace to deoxidize the 70
ide material, the combination of a plurality of
more easily reducible material.
closely-spaced bars forming a multiple channel
Accordingly, by making the bed on the top
hearth, said bars having a cross-section forming
hearth of Fig. 7 thin, by adjusting its dam M’
upwardly venturi-shaped slots between them,
to a low height, and gradually increasing the
depth of the beds on the succeeding hearths by 75 means for supplying reducing gas to the lower
ends of said slots for upward ?ow therethrough,
and means for feeding a bed of the material on
said hearth for treatment by said gas at reducing
said bars to vary the width of said slots and the
consequent supply or reducing gas therethrough.
6. In apparatus for reducing ?nely-divided ox
ide material, the combination of a plurality of
5. In apparatus for reducing ?nely-divided ox 5 closely-spaced parallel bars forming an oxide
ide material,-the combination of a plurality of
material bed supporting hearth having gas slots
closely-spaced parallel bars of substantially tri
angular cross-section forming a hearth having a
between the bars, -a gas chamber beneath said
hearth, means for supporting said bars, and
plurality of substantially V-shaped grooves hav
mechanisms for spreading said means to each
ing bottom slots, a gas chamber beneath said 10 side of the center of said hearth to spread the
hearth, means for supplying reducing gas to said
bars supported thereby for increasing the width
chamber for ?ow through said hearth slots, means
of the gas slots between the bars, whereby the
for feeding a bed of the ‘?nely-divided material
supply of gas to the bed is increased at will.
to one end of said hearth for reduction by said
gas, and means for adjusting the spacing between 15
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